Hollow head poppet valve



Aug. 1, 1944. r A T;\CQLWELL 2,354,947

HOLLOW HEAD POPPET VALVE Filed Aug. 30, 1940 Patented Aug. 1, 1944 HOLLOW HEAD POPPET VALVE Archie T. Colwell, Cleveland, Ohio, assignor to.

Thompson Products Incorporated, Cleveland, Ohio, a corporation of Ohio Application August so, 1940, Serial No. 354,787

Claims.

This invention relates to poppet valves for internal combustion engines and especially exhaust poppet valves for internal combustion engines.

More specifically the invention relates to poppet valves formed from cap and stem body members integrally united together without appreciable heating of the parts for elimination of oxidation.

While hollow poppet valves having head caps welded to stem body members are known, these valves are not suitable for use in modernhigh compression internal combustion engines since the metal parts will not withstand the tremendous pressures and corrosive action of the gases in the engine. Likewise, ordinary welding of the caps to the body members will not produce satisfactory a hollow head metal poppet valve including a welded circular area of apreciable width defined by the ends of metal grain bands so as to confine said ends against exposure to corrosive action by gases in which the valve operates.

' A further object of the invention is to provide a hollow head metal poppet valve containing a cooling medium completely enclosed therein by means of a welded bond effected without raising the temperature of the coolant sufficiently to oxidize the same. 4

Other and further objects of the invention will become apparent to thoseskilled in the art from the following detailed description'of the annexed sheet of drawings which illustrates preferred embodiments of the invention.

ends of the grain bands are thus integrally united into a unitary part and the entire head area of the valve which is exposed to the corrosive gases in the internal combustion engine is defined by the sides only of metal grain bands. The sides of the grain bands resist corrosion much better than the ends of the bands, and, as a result, the valves of this invention will have a longer operating life. 7 A feature of the invention includes the provision of mating rim areas on the head caps and stem bodies, which areas are defined by the terminal ends of the metal grain bands. The rims are pressed together and a surge of' very high frequency current is passed between the mating rims to instantaneously. fuse the same together without, however, heating the remainder of the metal parts. Since hollow valves are frequently filled with metallic sodium as a coolant, and since sodium is readily oxidized, the welding step used in this invention is of great importance in preventing oxidation of the sodium. The welding step likewise prevents oxidation of the metal caps and stem body members thereby preventing the formation of an oxide coating on the interiors of these members. Such an oxide coating interferes with heat transfer between the valve body and the coolant since it prevents the coolant from making good contact with the metal.,

On the drawing:

Figure 1 is a side elevational view of a'hollow head poppet valve according to this invention.

Figure 2 is a vertical cross-sectional view taken through a valve head cap used in making the valves of this invention.

Figure 3 is a fragmentary vertical cross-sectional view taken through a stem body member used in making the valves of this invention.

Figure 4 is a cross-sectional view taken through the cap and body members of Figures 2 and 3,

illustrating the same mounted inv position for welding.

. inclined valve seat portion i5.

Figure 5 is an electrical diagram illustrating a flash welding apparatus for uniting the parts shown in Figure 4.

Figure 61s a fragmentary vertical cross-sectional view of the valve formed from the parts shown in Figure 4 and illustrating the welded bond integrally uniting the parts.

Figure 6A is a view similar to Figure 6 but i1lustratlng the valve with a; cast head cap.

Figure 7 is a fragmentary vertical cross-sectional view of a modified form of valve according to this invention. y

Figure 7A is a view similar. to Figure 7 but illustrating the modified valve form with a cast head cap.

As shown on the drawing:

In Figure l the reference numeral l0 designates generally a hollow poppet valve having a cylindrical stem portion I provided with a solid bottom end I 2 having peripheral grooves i3 therein for receiving a valve spring retainer lock. The upper end H of the stem ii is flared outwardly to an The; outwardly flaring portion I4 is conveniently referredto as a tulip" end on the valve stem. The -valve l0 has a dome-shaped top IS. The interior of the valve has a cavity II flaring outwardly at the head portion into close proximity with the valve seat I! and extending into the stem portion H as shown in dotted lines. This cavity. I1 is partially filled with a coolant C such as metallic sodium. In operation the head area of the valve is heated by the exhaust gases surrounding the valve head. The metallic sodium in the cavity II will be melted and will serve to dissipate heat down into the stem portion II of the valve thereby cooling the head end of the valve.

As shown in Figures 2 and 3, the valve I0 is built up from a head cap member 2| and a stem body member 2|. The cap member 2| is forged and machined from a circular metal disk to form a dependent circular flange 22 with a flat rim bottom 22 and a dome-shaped top wall 24. A recess 24a bounded by the flange 22 and the top wall 24 is thus provided in the cap 2|. As shown, the metal grain bands 2| extend longitudinally through the cap member and have their terminal ends at the flat rim 22. Thus all exterior surfaces of the cap 2| are defined by the sides only of the metal grain bands. The rim 22 is defined by the ends of the metal grain bands but, as well be here- 20 lnafter explained, this rim portion is confined in a weld area which is not exposedin the finished valve.

The stem body 2| is formed by forging and machining a solid metal rod having the grain bands extending longitudinally from'end to-end thereof. The body member 2| is composed of a hollow tubular stem portion 22 which is flared out at its upper end 21 to define an open topped cavity 2|. The flared out portion 21 forms the tulip end of the stem body. The upper end of the flared out portion 21 is flanged as at 2| to provide a flat walled circular-rim 2| around the mouth of theportion with their sides only. The cavity 22 in the stem body 2| can extend down through the stem portion 2| in the manner shown in dotted lines in Figure l, or can continue as a straight cylindrical bore into closer proximity with the closed bottom end of the stem.

erably provided with a circumferential groov 22 for a purpose to be hereinafter described.

Porunitingthecap 2| tothestembodyfl the rim" ofthecapisseatedontherlmll ofthe the cavity 22 in the body 2| is partially filled with acoola'n'tcsuchasmetallic sodium.

In order to permanently unite the cap 2| to the body 2| without oxidizing the coolant or without distorting the metal body members, the stem member 2| is clamped in a supporting electrode 22 having an electrical connection 22 with the apparatus shown in Figure 5. The cap 2| is pressed down on top of the stern body 2| by means of a second electrode 24 having a recess 24a adapted to receive the cap and being connected through a wire 25 with the apparatus shown in Figure 5.

In Figure 5 the reference numeral 2| designates power lines supplying alternating current to a transformer 21. A half-wave rectifler 2| is provided in the circuit and includes a plate 2| receiving current fronrthe transformer 21. The flla ment 4| of the rectifier is heated bya battery or other source of current 4| in accordance with usual rectifier installation practice.

side of the condenser 42 is directly connected with the transformer 21 as shown.

The condenser 42 discharges through a variable inductor element 44 connected to the wire 2| 5 and to the electrode 24. The other side of the condenser 42 is directly connected through the wire 22 to the electrode 22.

When the cap 2| is mounted on the coolantfllledstembodyfl asshowninl igure4andthe lo mating rims 22 and 2| are-pressed together under 15 the welding area. In welding an area of about two square inches current will flow at the rate of 150,000 amperes at 4000 volts from an 8000 microfarad condenser. The weld is completed in less than /1000 of a second.

The great speed of the welding operation prevents oxidation. The weld is probably not over 0.0005 inch in dep h.

Intheoperationofthecircuitshowninl'igilre 5, the condenser 42 is charged for one or two seccndsandthendischargesitsloadtotheelectrodes" and 24. 'Iheoapflandthestembody -2| are thus charged with the high frequency currentandtherims22snd2|willbeinstantaneously welded together. Because the welding. is eiiected instantaneously the high frequency currentdischarge between the pressed-together parts does not heat the entire areaofthecsp and stembody and the steel parts are thus not oxidised. Likew sethesodlumorothercoolantcinthestem body is retained in an unoxidised state. This instantaneous welding may therefore be termed a cold" welding process which maintains the crisinal metallurgical conditions of the parts being 4 weldedvlw and eliminates all oxidation of the valve The welded-together cap 2| and stembody 2| are then removed from the electrodes 22 and 2| and.asshownlnl'lgure|,theresultingvslve|l has a weld area 4| of appreciable width \miting therlmsofthecapandstemmembersintcsn 4s integrslpartandconflningtheendsofthegrain The outer side wall of the flange 2| is prefbands" and 2|. The groove 22 around the peripheryoftheflanseflisfllledwithabearing alloy ring 41. Sielllte is preferably used. This 'alloyring4lcahbeweldedintothegrofle22lw I w meansofanacetyleneweldingtorchandtheweldbody as shown in Figure 4. First of all, however,

ss tive to dissipate heat from the flange area 2| A variable resistor 42 is mounted in the circuit from the rectifier 2| and a variable condenser 42 receives the charge from the rectifier. The other is and the terminal ends of the grain throughout theentire valve. The head of the valve 4| is preferably placed down what the stelliteseatisweldedinpositionsothatthemtire headareawiilbeoooledbyth moltensodimn.

Insteadofthecap2|andstembody2| being intheshspeshowninPlgures2,2,4and8,acap 2|ashowninFlgure7,andastembody2|ashm .inl'igure'lcanbeusedtoformamodifledtypeof valve 4lasccordingtothisinvzntion.

The cap 2| is formed by forging and machining insmannersimliartothatdescribedabovein connection with the cap 2| but the cap isprovided withadependentflangelhonwhichavalveseat surface 22b can be formed, or in which a groove can be cut to receive a Btclilte seating rint. In the cap 2|a, the valve seatorthevalveseatgrcove isprovidedbythecapinstesdofbythestembody; The grain bands 2 of the- 1D Ila define all exterior surfaces of thecap with their sideaoniy bands are a If desired, as shown in Figures 6A otherwise than necessitated confined in the vertical'weld area "a uniting the parts together. The stem body 2 la is flared straight outwardly and the ends of the grain bands Ila in this stem terminate in a vertical rim adapted to mate with the vertical rim provided by the fiange 22a of the cap. The rim of the cap is press fitted onto the rim of the body member and the weld area 46a formed by the electrical surge described above. The weld area 46a confines the ends of the grain bands.

From the above description it should be under stood that the valves of this invention are made from separate caps and stem bodies which are integrally united along a weld area of appreciable width. This weld area confines all grain band .ends of the metal parts so that the head portion of the valve is defined only by the sides of metal grain bands. The welding is effected when the metal parts are urged together under pressure so asto bring rims defined by the grain band ends thereof into good contacting relation. A surge of high frequency electric current will instantaneously form the weld-without oxidizing any of the interior surface of the valve parts. The weld formed by the surge of current between the rims is essentially a complete surface bond which does not change metallurgical properties of the parts.

However, the bond is complete over the entire k on the head cap which overlap the groove are covered by the welded-in seating ring as shown in, Figure 6. v

and 7A, the cap members II or 20a of Figures 6 and 7 can be replaced with cast caps 20 and 200' respectively to form modified valves 4'' and Na. In Figures 8A and 7A, parts identical with those shown in Figures 6 and '1 have been marked with the same reference numerals. The cast caps 20' and 20a can thus be made of alloys which are not easily forged or machined. For example, iron alloys own as Nlchrome steels; nickel, molybdenum and iron alloys known'as Hastelloy steels; nonferrous nickel-chromium alloys known as Brightray; and chromium tungsten alloys known as stellite, can be used to effectively resist the cor.-

when as described above. The resulting poppet valves thus can have forged metal stems which resist the operating stresses resulting from reciprocation of the valves and highly corrosionreslstant caps.

It will, of course, be understood that various ing a one-piece metal cap having a dependent peripheral flange defining a rim of appreciable width, said cap having the metal grain bands thereof terminating in said rim and defining the exterior top and side walls of thecap with their sides only, a one-piece metal stem body member having an outwardly flaring hollow tulip end bounded by a circular rim of appreciable width, said body member having the metal grain bands thereof terminating in said rim and defining the exterior side walls of the body member with their sides only, and a weld integrally uniting said rims to unite the cap and body member for providing the valve with all of the exposed surfaces in the head area thereof defined only by the sides of the metal grain bands.

2. A hollow head metal poppet valve comprising a one-piece hollow metal cap having a dependent circular fiange with a fiat bottom rim portion of appreciable width, said cap having the metal grain bands thereof terminating in said rim bottom and defining the exterior top and side walls of the cap with their sides only, a onepiece metal stem body member having an outwardly flaring hollow tulip end bounded by a flat circular rim top of appreciable width, said body member having the metal grain bands thereof terminating in said rim top and defining the exterior side walls of the body member with their sides only, and a weld uniting said rims to confine the ends of the grain bands and provide the valve with exterior surfaces defined only by'the sides of the metal grain bands.

3. A hollow head poppet valve comprising a hollow cast corrosion-resistant metal head cap having a depending portion defining a rim surface of appreciable area, a forged stress-resisting metal stem body member having a hollow outwardly flaring tulip end terminating in a rim surface of appreciable area sized for mating wit the rim surface of the cap, said forged body member having the metal grain bands thereof terminating in the rim surface thereof and defining the exterior side walls of the body member with their sides only, and a weld integrally unit ing the cap and body members along their mating rim surfaces and covering the ends of the metal grain bands.

4. A hollow'head metal poppet valve compris- 7 ing a hollow metal head cap having a depending rim portion of appreciable width a metal stem body member having an outwardly flaring hollowtulip end bounded by a rim of appreciable width, said body member having the metal grain bands thereof terminating in said rim and defining the exterior side walls of the body member with their sides only, said depending-rim of the head can completely covering the rim of the body member to encase the grain band ends, and a weld integrally uniting the rim surfaces.

5. A hollow head poppet valve comprising a hollow cast corrosion-resistant metal head cap having a depending portion defining a rim surface of appreciable area, a forged stress-resistdetails of construction may be varied througha wide range without departing from the principles of this invention and it is, therefore, not

the purpose to limit the patent granted hereon I by thescope of the appended claim. I

v I claim asmy invention:

1. A hollow head metal poppet-valve comprising metal hollow'stem body member terminatinl in a rim surface of appreciable area sized for mating with the rim surface of the cap, saidforged body member having the metal grain bands thereof terminating in the rim surface thereof and defining the exterior side walls of the body member with their sides only, and a weld integrally uniting the cap and body members along their mating rim surfaces and covering the ends of the metal grain bands.

1 ARCHE T. COLWELL 

